Reduced height camera modules

ABSTRACT

Electronic devices may include camera modules. A camera module may include an anamorphic lens and an image sensor having an array of asymmetrical image pixels. The array may be a square array arranged in pixel columns and pixel rows. The square image pixel array may include more pixel columns than pixel rows and may be located completely within the image circle of the anamorphic lens. The asymmetrical image pixels may each have a width that is smaller the height of that image pixel. The asymmetrical image pixels may be rectangular image pixels or diamond-shaped image pixels. The anamorphic lens may project a distorted image onto the array of asymmetrical image pixels. The width of each asymmetrical image pixel may be smaller than the height of that image pixel by an amount that corresponds to the distortion of the image by the anamorphic lens.

This application claims the benefit of provisional patent applicationNo. 61/642,422, filed May 3, 2012, which is hereby incorporated byreference herein in its entirety.

BACKGROUND

This relates generally to imaging devices, and more particularly, toimaging devices with anamorphic lenses and asymmetrical image pixels.

Camera modules having image sensors and lenses are commonly used inelectronic devices such as cellular telephones, cameras, and computersto capture images. In a typical arrangement, an electronic device isprovided with an image sensor with an array of square image pixelsarranged in pixel rows and pixel columns. A lens is used to focus imagelight onto the image sensor. The lens must illuminate the full imagesensor for a given field-of-view. In other words, an image sensor isplaced at a distance from the lens such that the image circle of thelens at the location of the image sensor is large enough that the fullimage pixel array fits within the image circle. For this reason, thez-height of the camera module is limited by the largest diagonaldimension of the image sensor.

Image sensors commonly include image pixel arrays with more pixelcolumns than pixel rows. For example, standard image sensors includeeither four pixel columns for every three pixel rows for still imagecapture sensors or sixteen pixel columns for every nine pixel rows forvideo image capture sensors. Conventional camera modules using thesetypes of configurations therefore have an increased z-height in order tolocate the image sensor at a location at which all of the pixel columnsfit within the image circle of the lens.

It would therefore be desirable to be able to provide improved cameramodules with reduced z-heights that generate standardized still andvideo image output.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of an illustrative electronic device that contains acamera module with anamorphic lenses and asymmetrical image pixels inaccordance with an embodiment of the present invention.

FIG. 2 is a perspective view of an illustrative camera module having anarray of anamorphic lenses in accordance with an embodiment of thepresent invention.

FIG. 3 is a diagram of an illustrative image sensor array of the typethat may be used with the lens array of FIG. 2 in a camera module inaccordance with an embodiment of the present invention.

FIG. 4 is an illustrative diagram showing how an asymmetric image of ascene may be projected onto a square image pixel array havingasymmetrical image pixels using an anamorphic lens in accordance with anembodiment of the present invention.

FIG. 5 is an illustrative diagram showing a square image pixel arrayhaving asymmetrical image pixels within an image circle of an anamorphiclens in accordance with an embodiment of the present invention.

FIG. 6 is a top view of a portion of an illustrative image pixel arrayshowing how image pixels in the image pixel array may have asymmetricaldimensions in accordance with an embodiment of the present invention.

FIG. 7 is a top view of a portion of an illustrative image pixel arrayshowing how diagonally oriented, diamond-shaped image pixels in theimage pixel array may have asymmetrical dimensions m accordance with anembodiment of the present invention.

FIG. 8 is a cross-sectional side view of an illustrative camera modulehaving an allomorphic lens and asymmetrical image pixels in accordancewith an embodiment of the present invention.

FIG. 9 is a block diagram of a processor system that may include acamera module of the type shown in FIG. 8 in accordance with anembodiment of the present invention.

DETAILED DESCRIPTION

Camera modules are widely used in electronic devices such as digitalcameras, computers, cellular telephones, and other electronic devices.These electronic devices may include image sensors that gather incominglight to capture an image. The image sensors may include arrays of imagepixels. The pixels in the image sensors may include photosensitiveelements such as photodiodes that convert the incoming light intodigital data. Image sensors may have any number of pixels (e.g.,hundreds or thousands or more). A typical image sensor may, for example,have hundreds, thousands, or millions of pixels (e.g., megapixels).

FIG. 1 is a diagram of an illustrative electronic device that uses animage sensor to capture images. Electronic device 10 of FIG. 1 may be aportable electronic device such as a camera, a cellular telephone, avideo camera, or other imaging device that captures digital image data.Camera module 12 may be used to convert incoming light into digitalimage data. Camera module 12 may include one or more anamorphic lensessuch as lenses 14-1 and 14-N and one or more corresponding image sensorssuch as image sensors 16-1 and 16-N. During image rapture operations,light from a scene may be focused onto one or more image pixel arrays 17of image sensors 16-1 . . . 16-N using respective anamorphic lenses 14-1. . . 14-N. Lens array 14 and image sensor array 16 may be mounted in acommon package and may provide image data to processing circuitry 18.

Each image sensor image include one or more arrays 17 of image pixels140. Image pixels 140 of each image pixel array may have an asymmetricalshape that corresponds to distortion of an image of a scene by lenses inarray 14. For example, lens 14-1 may be an anamorphic lens that projectsimage light from a portion of a scene that is wider than it is tall ontoa square image pixel array 17. That is, anamorphic lens 14-1 maycompress the horizontal dimension of the image. Image pixels 140 inimage sensor 16-1 may have a width that is smaller than their height sothat the compression ratio of lens 14-1 is matched by the dimensions ofpixels 140. In this way, a relatively wide scene can be projected onto asquare image pixel array while projecting light from square portions ofthe scene into single asymmetrical image pixels using the anamorphiclens. This type of square image pixel array having asymmetrical imagepixels may be placed closer to a lens than as conventional image sensorusing a standard lens. The total z-height Z of camera module 12 maytherefore be reduced in comparison with conventional camera modules.

A properly dimensioned (undistorted) image of the scene can be generatedby reading out image signals from asymmetrical image pixels 140 intocorresponding square output image pixels, thereby generating arelatively wide image of the scene that corresponds to the relativelywide field-of-view of camera module 12.

Processing circuitry 18 may include one or more integrated circuits(e.g., image processing circuits, microprocessors, storage devices suchas random-access memory and non-volatile memory, etc.) and may beimplemented using components that are separate from camera module 12and/or that form part of camera module 12 (e.g., circuits that form partof an integrated circuit that includes image sensor array 16 or anintegrated circuit within module 12 that is associated with image sensorarray 16). Image data that has been captured by camera module 12 may beprocessed and stored using processing circuitry 18. Processed image datamay, if desired, be provided to external equipment (e.g., a computer orother device) using wired and/or wireless communications paths coupledto processing circuitry 18.

There may be any suitable number of lenses in lens array 14 and ansuitable number of image sensors in image sensor array 16. Lens array 14may, as an example, include N*M individual anamorphic lenses arranged inan N×M two-dimensional array. The values of N and M may be equal to one,equal or greater than two, may be equal to or greater than three, mayexceed 10, or may have any other suitable values. Image sensor array 16may contain a corresponding N×M two-dimensional array of individualimage sensors having arrays of asymmetrical image pixels. The imagesensors may be formed on one or more separate semiconductor substrates.With one suitable arrangement, which is sometimes described herein as anexample, the image sensors are formed on a common semiconductorsubstrate (e.g., a common silicon image sensor integrated circuit die).Each image sensor may be identical or there may be different types ofimage sensors in a given image sensor array integrated circuit. Eachimage sensor may be a Video Graphics Array (VGA) sensor with aresolution of 480×640 sensor pixels (as an example). Other types ofsensor pixels may also be used for the image sensors if desired. Forexample, images sensors with greater than VGA resolution sensor (e.g.,image sensors that are 4096 pixels wide and 3072 pixels high or imagesensors that are 4480 pixels wide and 2520 pixels high) or less than VGAresolution may be used, image sensor arrays in which the image sensorsare not all identical may be used, etc.

Each image pixel array 17 may be provided with a color filter. The colorfilter may be a Bayer pattern color filter array or each image pixelarray may be provided with a color filter of a single color. Asexamples, the color filters that may be used for the image sensor pixelarrays in the image sensors may be red filters, blue fitters, and greenfilters. Each filter may form a color filter layer that covers the imagesensor pixel array of a respective image sensor in the array. Otherfilters such as infrared-blocking filters, filters that block visiblelight while passing infrared light, ultraviolet-light blocking filters,white color filters, etc. may also be used. In an array with numerousimage sensors, some of the image sensors may have red filters, some mayhave blue color filters, some may have green color filers, some may havepatterned color filters (e.g., Bayer pattern filters, etc.), some mayhave infrared-blocking filters, some may have ultraviolet light blockingfilters, some may be visible-light-blocking-and-infrared-passingfilters, etc.

Processing circuitry 18 (e.g., processing circuitry integrated ontosensor array integrated circuit 16 and/or processing circuitry on one ormore associated integrated circuits) may be used to generate undistortedoutput images using image data captured by one or more of image pixelarrays 17.

FIG. 2 is a perspective view of an illustrative camera module having anarray 14 of lenses (e.g., lenses such as anamorphic lenses 14(1,1), and14(4,4)). The array of lenses may, for example, be a rectangular arrayhaving rows and columns of anamorphic lenses. The lenses may all beequally spaced from one another or may have different spacings. Theremay be any suitable number of lenses in the array. In the FIG. 2example, there are four rows and four columns of lenses.

An illustrative sensor array of the type that may be used with the lensarea of FIG. 2 is shown in FIG. 3. As shown in FIG. 3 sensor array 16may include image sensors such as sensor 16(1,1), 16(4,1), and 16(4,4).The array of FIG. 3 has sixteen image sensors, but, in general, array 16may have any suitable number of image sensors (e.g., one image sensor,two or more sensors, four or more sensors, ten or more sensors, 20 ormore sensors, etc.). Each image sensor may include one or more imagepixel arrays 17 having asymmetrical image pixels 140. In one suitableexample that is sometimes discussed herein as an example, camera module12 may include one image sensor having one image pixel array and onecorresponding anamorphic lens.

A diagram of a relatively wide image of a scene that is projected onto asquare image pixel array having asymmetrical pixels is shown in FIG. 4.As shown in FIG. 4, the field-of-view of camera module 12 may include areal world scene 20. Real world scene 20 may include objects such asobject 22 (e.g., a mountain) and object 24 (e.g., the moon). Ananamorphic lens such as lens 14(1,1) may project scene 20 onto imagepixel array 17 (e.g., image pixel array 17 of image sensor 16(1,1)having asymmetrical image pixels 140).

Scene 20 (e.g., the portion of the scene in the field-of-view of cameramodule 12) may have a width WS and a height HS. Width WH may be greaterthan height HS. As examples, width WS and height HS may have a 4:3 ratio(i.e., width WS may be fourth thirds of height HS) or width WS andheight HS may have a 16:9 ratio (i.e., width WS may be sixteen ninths ofheight HS).

Anamorphic lens 14(1,1) may project a distorted image of scene 20 ontoarray 17. As shown in FIG. 4, the distorted image may be a horizontallycompressed image that includes horizontally compressed object imagessuch object images 22I and 24I (corresponding respectively to objects 22and 24).

Image pixel array 17 may be a square image pixel array (e.g., imagepixel array 17 may have a width and a height that are equal) having,sides of length LI. Image pixels 140 may be asymmetrical image pixelshaving a height that is larger than their width so that the portion ofthe scene that would have fallen in a square image pixel with a circularlens falls into a single asymmetrical image pixel 140 after passingthrough lens 14(1,1).

As shown in FIG. 5, image circle 30 of an asymmetrical lens such as lens14(1,1) may have a diameter D at the location of image pixel array 17.Diameter D may be large enough that the largest diagonal dimension ofimage pixel array 17 fits within circle 30. In this way, all imagepixels 140 of image pixel array 17 can be illuminated by light fromscene 20 that has passed through an asymmetrical lens such as lens14(1,1).

The z-height of camera module 12 (e.g., height Z of FIG. 1) depends onthe focal length of the lens used to project image light onto the imagesensor as described by the following equation:F=D/(2 tan(FOV/2)),in which F is the focal length of the lens, D is the diameter of theimage circle of the lens (as shown in FIG. 5), and FOV is the desiredfield-of-view of the particular application in which camera module 12 isto be implemented. The z-height of camera module 12 can therefore bereduced, independent of the desired field-of-view, by reducing thenecessary image circle diameter D. An image sensor having an image pixelarray with asymmetrical image pixels 140 can fit into a relativelysmaller image circle (i.e., an image circle with a smaller diameter D)than a conventional image sensor with the same number of square imagepixels.

As shown in FIG. 5, image pixels 140 may be arranged in pixel rows 32and pixel columns 34. Image pixel array 17 may include more pixelcolumns 34 than pixel rows 32. As examples, image pixel array 17 mayinclude 4096 pixel columns and 3072 pixel rows, 4480 pixel columns and2520 pixel rows, other numbers of pixel columns and pixel rows having aratio of 4 pixel columns for every three pixel rows other numbers ofpixel columns and pixel rows having a ratio of sixteen pixel columns forevery nine pixel rows or other suitable numbers of pixel columns andpixel rows. Each image pixel 140 may have a width that is less than itsheight so that image pixel array 17 has a square shape with sides ofequal length LI while accommodating more pixel columns 34 than pixelrows 32.

FIGS. 6 and 7 show examples of arrangements for asymmetrical imagepixels 140. In the example of FIG. 6, pixels 140 are rectangular imagepixels each having a width WP and a height HP. As shown in FIG. 6, widthWP may be less than height HP. In configurations in which image pixelarray 17 has four pixel columns 34 for every three pixel rows 32, widthWP may be approximately 75% (e.g., between 70 percent and 80 percent orbetween 74 percent and 76 percent) of height HP. In this type ofconfiguration, the image circle diameter D in which image pixel array 17will fit is reduced in size by approximately 15.15% in comparison withconventional square pixels. However, this is merely illustrative.

In configurations in which image pixel array 17 has sixteen pixelcolumns for every nine pixel rows, width WP may be approximately 56.25%(e.g., between 50 percent and 60 percent or between 56 percent and 57percent) of height HP. In this type of configuration, the image circlediameter D in which image pixel array 17 will fit is reduced in size byapproximately 30.7% in comparison with conventional square pixels.However, configurations in which image pixels 140 are rectangular imagepixels having edges that are aligned with edges of the image sensor aremerely illustrative.

As shown in FIG. 7, image pixels 140 may have a substantially diamondshape in which the edges of image pixels 140 are not parallel to theedges of the image sensor (e.g., the edges of pixels 140 may be formedat an angle other than 180 degrees or 90 degrees with respect to theedge of the image sensor). In configurations in which image pixels 140are diamond shaped image pixels and image pixel array 17 includes fourpixel columns 34 for every three pixel rows 32, the image circlediameter D in which image pixel array 17 will fit is reduced in size byapproximately 14.93% in comparison with conventional square pixels thatare formed at an angle with respect to the edges of the image sensor.Image pixels of the types shown in FIGS. 6 and 7 may befront-side-illuminated (FSI) image pixels or backside-illuminated (BSI)image pixels.

As shown in FIG. 8, the z-height of a camera module 12 having anamorphiclenses and asymmetrical image pixels may be reduced by an amount thatcorresponds to the reduction in size of the image circle in comparisonwith conventional square image sensors. For example, camera module 12may have an anamorphic lens 14N with a nodal point 47 formed at az-distance ZAV from a video image sensor 16AV having asymmetrical imagepixels. In configurations in which image sensor 16AV includes imagepixels 140 having width WP that is approximately 56.25% of their heightHP, ZAV may be reduced by approximately 30.7% in comparison with cameramodules having circular lenses and square pixels.

As another example, camera module 12 may have an anamorphic lens 14Nwith a nodal point 47 that is formed at a z-distance ZAS from a stillimage sensor 16AS having asymmetrical image pixels. In configurations inwhich image sensor 16AS includes image pixels 140 having width WP thatis approximately 75% of their height HP, ZAS may be reduced byapproximately 15.15% in comparison with camera modules having circularlenses and square pixels. In configurations in which image sensor 16ASincludes image pixels 140 having width WP that is approximately 56.25%of their height HP, ZAS may be reduced by approximately 30.7% incomparison with camera modules having circular lenses and square pixels.In configurations in which image sensor 16AS includes diamond shapedimage pixels 140 of the type is shown in FIG. 7, ZAS may be reduced byapproximately 14.93% in comparison with camera modules having circularlenses and square pixels with edges formed at an angle with respect tothe edges of the image sensor.

FIG. 9 shows in simplified form a typical processor system 300, such asa digital camera, which includes an imaging device such as imagingdevice 200 (e.g., an imaging device 200 such as camera module 12 of FIG.1 employing anamorphic lenses and asymmetrical image pixels as describedin connection with FIGS. 1-8). Processor system 300 is exemplary of asystem having digital circuits that could include imaging device 200.Without being limiting, such a system could include a computer system,still or video camera system, scanner, machine vision, vehiclenavigation, video phone, surveillance system, auto focus system, startracker system, motion detection system, image stabilization system, andother systems employing an imaging device.

Processor system 300, which may be a digital still or video camerasystem, may include a lens such as lens 396 for focusing an image onto apixel array such as pixel array 201 when shutter release button 397 ispressed. Processor system 300 may include a central processing unit suchas central processing unit (CPU) 395. CPU 395 may be a microprocessorthat controls camera functions and one or more image flow functions andcommunicates with one or more input/output (I/O) devices 391 over a bussuch as bus 393. Imaging device 200 may also communicate with CPU 395over bus 393. System 300 may include random access memory (RAM) 392 andremovable memory 394. Removable memory 394 may include flash memory thatcommunicates with CPU 395 over bus 393. Imaging device 200 may becombined with CPU 395, with or without memory storage, on a singleintegrated circuit or on a different chip. Although bus 393 isillustrated as a single bus, it may be one or more buses or bridges orother communication paths used to interconnect the system components.

Various embodiments have been described illustrating camera moduleshaving anamorphic lenses and asymmetrical image pixels. Camera moduleshaving anamorphic lenses and asymmetrical image pixels may have reducedz-heights in comparison with camera modules having circular lenses andsquare pixel.

A camera module may include one or more anamorphic lenses that focusimage light from a scene onto one or more corresponding image sensorswith asymmetrical image pixels. The asymmetrical image pixels may have ashape that corresponds to distortion of the scene by the anamorphiclens. For example in configurations in which an anamorphic lenscompresses the horizontal dimension of an image by 25%, the asymmetricalpixels may have a width that is 25% smaller than their height. In thisway, image pixel values from the asymmetrical image pixels may be readout and processed as if they were square image pixels in order toreconstruct an undistorted image of a scene without the need forsoftware-based distortion corrections.

An image sensor may include an image pixel array having pixel columnsand pixel rows. The image pixel array may include more pixel columnsthat pixel rows. As examples, the image pixel array may be a squareimage pixel array that includes four pixel columns for every three pixelrows for still image capture operations or sixteen pixel columns forevery nine pixel rows for video image capture operations. The imagepixels may have a corresponding width to height ratio such as a 3:4width to height ratio or a 9:16 width to height ratio so that the imagepixel array can accommodate more pixel rows than pixel columns in asquare array.

The foregoing is merely illustrative of the principles of this inventionwhich can be practiced in other embodiments.

What is claimed is:
 1. A camera module, comprising: an anamorphic lenshaving a corresponding image circle and a corresponding compressionratio; and an image sensor having a square image pixel array arranged inpixel columns and pixel rows, wherein the square image pixel arrayincludes more pixel columns than pixel rows, wherein the square imagepixel array is located entirely within the image circle of theanamorphic lens, and wherein the square image pixel array comprises: aplurality of rectangular image pixels having a height and a width,wherein a ratio of the height to the width is based on the compressionratio of the anamorphic lens, and wherein the ratio of the height to thewidth is between 0.7 and 0.8.
 2. The camera module defined in claim 1wherein the square image pixel array includes four pixel columns forevery three pixel rows.
 3. A camera module, comprising: an anamorphiclens; and an image sensor having an array of asymmetrical image pixels,wherein the anamorphic lens projects a distorted image onto the array ofasymmetrical image pixels, wherein each asymmetrical image pixel has ashape that is based on distortion of the distorted image, wherein eachasymmetrical image pixel has a width and a height, and wherein a ratioof the width of each asymmetrical image pixel to the height of thatasymmetrical image pixel is between 0.5 and 0.6.
 4. The camera moduledefined in claim 3 wherein the distorted image comprises a horizontallycompressed image.
 5. The camera module defined in claim 4 wherein eachasymmetrical image pixel has a width and a height and wherein the widthof each asymmetrical image pixel is smaller the height of that imagepixel by an amount that corresponds to the distortion of the distortedimage.
 6. The camera module defined in claim 3, further comprisingprocessing circuitry configured to generate an undistorted image usingimage signals from the asymmetrical image pixels.
 7. The camera moduledefined in claim 3 wherein the image sensor is a video image sensor. 8.The camera module defined in claim 3 wherein the image sensor is a stillimage sensor.
 9. The camera module defined in claim 3, furthercomprising: an additional anamorphic lens; and an additional imagesensor having an additional array of asymmetrical image pixels, whereinthe additional anamorphic lens projects an additional distorted imageonto the additional array of asymmetrical image pixels.
 10. A system,comprising: a central processing unit; memory; input-output circuitry;and an imaging device, wherein the imaging device comprises: ananamorphic lens, and an image sensor having an array of asymmetricalimage pixels, wherein the anamorphic lens projects a distorted imageonto the array of asymmetrical image pixels, wherein each asymmetricalimage pixel has a width and a height, and wherein the width of eachasymmetrical image pixel is smaller than the height of that image pixelby an amount proportional to a distortion of the distorted image by theanamorphic lens, and wherein a ratio of the width of each asymmetricalimage pixel to the height of each asymmetrical image pixel is between0.5 and 0.6.
 11. The system defined in claim 10 wherein the anamorphiclens has a corresponding image circle, wherein the array of asymmetricalimage pixels is a square array of asymmetrical image pixels having pixelrows and pixel columns, and wherein the square array of asymmetricalimage pixels is located within the image circle of the anamorphic lens.12. The system defined in claim 11 wherein the square array ofasymmetrical image pixels includes more pixel columns than pixel rows.13. The camera module defined in claim 1, wherein the ratio of theheight to the width is equal to the compression ratio of the anamorphiclens.